code: def shell(cmd: List[str]) -> Optional[str]:
      """Simple wrapper for calling docker,.
  
      returning None on error and the output on success
      """
      try:
          return (
              subprocess.check_output(
                  ["docker"] + cmd, stderr=subprocess.STDOUT
              )
              .decode("utf8")
              .strip()
          )
      except subprocess.CalledProcessError as e:
          print(e)
          return None
  
imports: import json
  import logging
  import os
  import subprocess
  from typing import Any, Dict, List, Optional, Tuple, Union
  import requests
  from dockerpycreds.utils import find_executable
  from wandb.docker import auth, www_authenticate
  from wandb.errors import Error
label_desc: Use image node_id 1 for calling a global function with example usage: shell(cmd) and returns: subprocess, None